This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We are investigating the development of cognitive and emotional influence over internal interval timing skills in adolescents. Interval timing refers to a person's "sense of time", that is, being able to judge how much time has elapsed and/or being able to reproduce a time interval when asked. We are seeking to determine whether timing processes are accurate in adolescents as compared to adults, as well as to determine if experimental manipulations of cognitive load and emotional valence will differentially interact with interval timing skills across development. We also plan to investigate the neural correlates of timing processes. This study will have a behavioral component and a neuroimaging component. We will use computer-based cognitive tasks as well as funtional magnetic resonance imaging (fMRI).